Efficient co-upcycling of glycerol and CO2 into valuable products enabled by a bifunctional Ru-complex catalyst.

Glycerol and CO2 are largely produced as by-products in modern industry. Herein, three Ru complexes bearing air- and water-stable NHC–nitrogen–nitrogen ligands are designed as bifunctional catalysts to upcycle glycerol and CO2 simultaneously. Among them, Ru complex 2 featuring an N–H structure shows the highest efficiency with TONs up to 300 000 and 387 000 for formate and lactate, respectively. 13C labelling experiments clearly manifest that formate is primarily derived from CO2. Furthermore, in situ FTIR spectra suggest that glyceraldehyde from glycerol might serve as a key intermediate to form lactate, while DFT calculations indicate that Ru complex 2 possesses the lowest reaction barriers and can form the Ru＝N intermediate, contributing to its higher activity. [ABSTRACT FROM AUTHOR]